diff options
Diffstat (limited to 'drivers/char/hw_random/ppc4xx-rng.c')
| -rw-r--r-- | drivers/char/hw_random/ppc4xx-rng.c | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/drivers/char/hw_random/ppc4xx-rng.c b/drivers/char/hw_random/ppc4xx-rng.c new file mode 100644 index 00000000000..b8afa6a4ff6 --- /dev/null +++ b/drivers/char/hw_random/ppc4xx-rng.c @@ -0,0 +1,156 @@ +/* + * Generic PowerPC 44x RNG driver + * + * Copyright 2011 IBM Corporation + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; version 2 of the License. + */ + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/platform_device.h> +#include <linux/hw_random.h> +#include <linux/delay.h> +#include <linux/of_platform.h> +#include <asm/io.h> + +#define PPC4XX_TRNG_DEV_CTRL 0x60080 + +#define PPC4XX_TRNGE 0x00020000 +#define PPC4XX_TRNG_CTRL 0x0008 +#define PPC4XX_TRNG_CTRL_DALM 0x20 +#define PPC4XX_TRNG_STAT 0x0004 +#define PPC4XX_TRNG_STAT_B 0x1 +#define PPC4XX_TRNG_DATA 0x0000 + +#define MODULE_NAME "ppc4xx_rng" + +static int ppc4xx_rng_data_present(struct hwrng *rng, int wait) +{ + void __iomem *rng_regs = (void __iomem *) rng->priv; + int busy, i, present = 0; + + for (i = 0; i < 20; i++) { + busy = (in_le32(rng_regs + PPC4XX_TRNG_STAT) & PPC4XX_TRNG_STAT_B); + if (!busy || !wait) { + present = 1; + break; + } + udelay(10); + } + return present; +} + +static int ppc4xx_rng_data_read(struct hwrng *rng, u32 *data) +{ + void __iomem *rng_regs = (void __iomem *) rng->priv; + *data = in_le32(rng_regs + PPC4XX_TRNG_DATA); + return 4; +} + +static int ppc4xx_rng_enable(int enable) +{ + struct device_node *ctrl; + void __iomem *ctrl_reg; + int err = 0; + u32 val; + + /* Find the main crypto device node and map it to turn the TRNG on */ + ctrl = of_find_compatible_node(NULL, NULL, "amcc,ppc4xx-crypto"); + if (!ctrl) + return -ENODEV; + + ctrl_reg = of_iomap(ctrl, 0); + if (!ctrl_reg) { + err = -ENODEV; + goto out; + } + + val = in_le32(ctrl_reg + PPC4XX_TRNG_DEV_CTRL); + + if (enable) + val |= PPC4XX_TRNGE; + else + val = val & ~PPC4XX_TRNGE; + + out_le32(ctrl_reg + PPC4XX_TRNG_DEV_CTRL, val); + iounmap(ctrl_reg); + +out: + of_node_put(ctrl); + + return err; +} + +static struct hwrng ppc4xx_rng = { + .name = MODULE_NAME, + .data_present = ppc4xx_rng_data_present, + .data_read = ppc4xx_rng_data_read, +}; + +static int __devinit ppc4xx_rng_probe(struct platform_device *dev) +{ + void __iomem *rng_regs; + int err = 0; + + rng_regs = of_iomap(dev->dev.of_node, 0); + if (!rng_regs) + return -ENODEV; + + err = ppc4xx_rng_enable(1); + if (err) + return err; + + out_le32(rng_regs + PPC4XX_TRNG_CTRL, PPC4XX_TRNG_CTRL_DALM); + ppc4xx_rng.priv = (unsigned long) rng_regs; + + err = hwrng_register(&ppc4xx_rng); + + return err; +} + +static int __devexit ppc4xx_rng_remove(struct platform_device *dev) +{ + void __iomem *rng_regs = (void __iomem *) ppc4xx_rng.priv; + + hwrng_unregister(&ppc4xx_rng); + ppc4xx_rng_enable(0); + iounmap(rng_regs); + + return 0; +} + +static struct of_device_id ppc4xx_rng_match[] = { + { .compatible = "ppc4xx-rng", }, + { .compatible = "amcc,ppc460ex-rng", }, + { .compatible = "amcc,ppc440epx-rng", }, + {}, +}; + +static struct platform_driver ppc4xx_rng_driver = { + .driver = { + .name = MODULE_NAME, + .owner = THIS_MODULE, + .of_match_table = ppc4xx_rng_match, + }, + .probe = ppc4xx_rng_probe, + .remove = ppc4xx_rng_remove, +}; + +static int __init ppc4xx_rng_init(void) +{ + return platform_driver_register(&ppc4xx_rng_driver); +} +module_init(ppc4xx_rng_init); + +static void __exit ppc4xx_rng_exit(void) +{ + platform_driver_unregister(&ppc4xx_rng_driver); +} +module_exit(ppc4xx_rng_exit); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Josh Boyer <jwboyer@linux.vnet.ibm.com>"); +MODULE_DESCRIPTION("HW RNG driver for PPC 4xx processors"); |